December 27, 2017

Deck the Shell with Balls of Poly

For majoid crabs, decorating is a way of life

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This article was published in Scientific American’s former blog network and reflects the views of the author, not necessarily those of Scientific American

I don’t know about you, but I don’t particularly enjoy decorating for the holidays. It feels like the decorations are up for two seconds before it’s time for me to go take them all down again. However, a

decorator crab lives to accessorize, and if what’s on offer are Christmas-colored polyester craft pompoms, well then Deck the Halls, baby!

This adorable tableau was brought to you by the laboratory of Danielle Dixson, where she, Rohan Brooker, and her students investigated the decorating preferences of the reef decorator crab Camposcia retusa using, as you see, craft-store pompoms soaked in water.

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When the crabs were given shelter, they attached fewer pompoms to themselves than shelter-less crabs, suggesting that decorating is about camouflaging oneself from predators rather than just looking fabulous.

Their chosen natural décor – sponges, algae, or miscellaneous detritus – often manufactures potent chemicals that may mask a crab’s smell or make the experience of eating crab legs distinctly distasteful. The crabs also preferred to decorate their hind legs over their central bodies, which may be due to their habit of hanging out at the entrance to their shelters with their legs sticking out.

Of course, the job of decorator crabs is made much easier by the fact that their exteriors are covered in convenient microscopic hooks. If only all the surfaces of my house were too!

Scale bar = 1 mm. Credit: Brooker et al. 2017

Hope you are having a festive holiday season, whether you heeded that irresistible urge to decorate or no.

Reference

Brooker, Rohan M., Enid C. Muñoz Ruiz, Tiffany L. Sih, Danielle L. Dixson, and Luke Holman. "Shelter availability mediates decorating in the majoid crab, Camposcia retusa." Behavioral Ecology (2017).

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